The invention relates to a method of transporting elongated objects, such as logs, by helicopter and a grapple adapted therefor.
Helicopters are commonly used to transport valuable timber from remote locations or from difficult terraine such as encountered in the Pacific Northwest of the United States of America or in the coastal region of British Columbia, Canada. Several factors have limited the use of helicopters. Firstly, it is widely recognized that the operation of helicopters is extremely expensive, and thus they must be utilized with great efficiency in order to provide a profitable operation. This means loading and unloading logs expeditiously so that the turn around time is decreased to the minimum possible, and the maximum number of logs are transported in a given period of time. Furthermore, it is highly advantageous to load the logs without the need of ground personnel. This removes the need for stationing personnel at the loading location to load the helicopter, and also improves the safety factor by removing persons who might be injured during the loading operation.
Systems have been developed in the past for transporting logs and other materials by use of a grapple suspended from a helicopter. One such system is shown in U.S. Pat. No. 4,152,019 to Jarman. However, such earlier systems have frequently not gained widespread acceptance due to real or perceived disadvantages. For example, in some cases a relatively complex installation is required within the helicopter or an auxiliary winch is required within the helicopter or an auxiliary winch platform must be suspended from the helicopter. In some cases there have been difficulties meeting safety and operational requirements. The need therefore remained, prior to this invention, for a relatively simple system for loading and transporting logs or other such objects by means of a grapple suspended from a helicopter while having a self-loading feature and a stable configuration during flight.